Note: Descriptions are shown in the official language in which they were submitted.
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OVERHEAD INDUSTRIAL LIGHT FIXTURE WITH
THERMAL CHIMNEY CONTIGUOUS TO RECESSED SOCKET
FIELD
The field relates generally to overhead industrial light fixtures, and more
specifically to overhead industrial light fixtures having high-intensity
discharge lamps.
BACKGROUND
Many different overhead industrial light fixtures exist to serve needs such as
factory and warehouse illumination and the like, and a number of advances have
been
made over the years. Among significant advances in industrial light fixtures
are the
fixtures disclosed in United States Patent Nos. 6,601,975 (Overhead Industrial
Light
Fixture With Two-Piece Housing); 6,394,869 (Method for Manufacture of Overhead
Industrial Light Fixture); and 6,467,927 (Overhead Industrial Light Fixture
With
Mounted Reflector), all of Ruud Lighting, Inc. Such fixtures provide
significant
advantages, including compactness, simplicity of manufacture, ease of
installation and
service, pleasing appearance, and other advantages set forth in the
disclosures.
Despite these and other such advances in the field there remains a need for
further improvement in industrial light fixtures, preferably without
compromising the
advantages previously provided including those related to ease of manufacture,
storage, shipment, installation, etc.
Overheating is a common problem for industrial light fixtures, and among the
overheating problems with certain devices of the prior art is a problem of
inadequate
heat dissipation away from power-related components such as ballasts, lamps
and
lamp sockets. Certain components, particularly capacitors, are limited in
their ability
to tolerate high temperatures. It is critical to the life of certain
components, mainly
those that are particularly heat-sensitive, that steps be taken to prevent
costly damage
or, worse, a premature end of the life of the fixture. Overheating can damage
power-
related components which comproniises the longevity of the light fixture and
its
components. Minimal gains in temperature reduction yield very substantial
gains in
component life and, therefore, in overall fixture longevity.
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While the concern of overheating has in some cases been addressed by use of
cooling fans, such fans are often loud and contrary to the highly desirable
goals of
fixture compactness, low cost, and operational reliability. Similarly, use of
barriers
and other insulating features have disadvantages as they increase
manufacturing costs
and also defeat the goal of compactness and ease of service. Plastic ballast
enclosures
may be used to thermally isolate the ballast; however, such enclosures are
contrary to
heat removal and can exacerbate problems.
In some cases, thermal protection devices to break circuits upon overheating
are utilized. However, under certain conditions such devices may fail to
perform
properly, thereby allowing a lighting fixture to overheat and possibly lead to
combustion. Such thermal protection devices also add cost.
Another possible approach to dealing with certain of the above problems and
shortcomings is use of a housing with one or more external power-related
components, such as the ballast. However, this approach complicates
installation,
increases cost, makes achieving a pleasing appearance difficult at best, and
is directly
contrary to the goal of compactness.
Another problem is that certain structures of the prior art may not be
particularly well-adapted to suppress and/or contain any combustion that might
occur.
In certain cases, the nature of the ballast (including manufacturing defects
or minimal
defects that may occur from handling or the like) or improper electrical
characteristics
or conditions can lead to ballast failures and shorts which in turn lead to
combustion
of materials (e.g., organic insulation materials). As can be seen, the goals
of
achieving cooling and suppressing oxidation in an overhead industrial light
fixture
tend to be at odds with each other. Accomplishing one of these critical goals
tends to
lead to loss of the other. The benefits realized in being able to accomplish
these two
goals in one fixture would be significant.
For one thing, facilitating cooling of the industrial light fixture tends to
keep
the components cool thereby enhancing the life of the components and the
entire
fixture and preserving overall quality. And, substantially reducing the inflow
and
outflow of combustion-supporting air in critical portions of an overhead
industrial
light fixture would tend to suppress and limit any combustion which might
occur, and
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thus reduce dangers typically associated with product failures. If these
critical
advantages could be combined in an overhead lighting fixture, the resulting
fixture
would have improved quality, endurance and longevity.
Accordingly, there remains in the art a need to provide an overhead industrial
light fixture that more effectively removes heat from the housing, without
sacrificing
other advantages of benefits realized from earlier development work.
OBJECTS
It is an object to provide an improved overhead industrial light fixture
overcoming some of the problems and shortcomings of the prior art.
Another object is to provide an overhead industrial light fixture which
facilitates dissipation of heat from the housing of the overhead industrial
light fixture
into the atmosphere.
Another object is to provide an overhead industrial light fixture in which air
infiltration is restricted to prevent combustion.
Another object is to provide an overhead industrial light fixture which is
well-
adapted to contain any combustion that might occur.
Another object is to provide an improved overhead industrial light fixture
that
is inexpensive to manufacture and easy to install.
Still another object is to provide an improved overhead industrial light
fixture
which is compact and yet free of problems of overheating critical components.
SUM[MARY
This invention is an improvement in overhead industrial light fixtures of the
type which include: a housing having a base member and a top member together
forming a space, the base member having an upwardly-extending middle portion
integral therewith which forms a recess; power-related components in the
space; and a
lamp-mounting socket in the recess. In the improvement, portions of the
housing
form a vertical airflow thermal chimney immediately adjacent to the recess and
extending through the housing from bottom to top, whereby heat transfer to the
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chimney and heat-dissipating airflow to the atmosphere are facilitated. The
socket
temperature drives convection of the air flow through the chimney.
In highly preferred embodiments, the thermal chimney and the recess together
form a contiguous open space, i.e., the chimney and the recess are not
isolated from
one another by a wall. In some other embodiments, the chimney and the recess
can
include a common wall therebetween which isolates the recess from the chimney
immediately adjacent thereto.
It is most preferred that both the base member and the top member are formed
of die-cast metal. In particularly preferred die-cast structures, the base
member and
the top member are configured to provide mating engagement thereby forming a
substantially enclosed space.
The base member preferably includes an annular lower chimney portion
terminating in a top edge. The top member includes an annular upper chimney
portion terminating in a lower edge and adjoining the top edge.
In highly preferred embodiments, the housing includes first and second
opposite endwalls. The middle portion of the base member and the thermal
chimney
together divide the space into a first region adjacent to the first endwall
and a second
region adjacent to the second endwall. In such embodiment, power-related
components include a capacitor in the first region and a ballast in the second
region.
It is most preferred that the top member is hinged with respect to the base
member at one of the endwalls. The base member and top member have first and
second mating hinge members each integrally formed therewith along adjacent
edges
thereof.
As used herein, the following terms have the meanings given below, unless the
context requires otherwise:
In referring to an overhead industrial light fixtures, the term "overhead"
refers
to fixtures which are typically mounted, directly or indirectly, on ceilings
or overhead
structural members of some sort, such as in factories, warehouses, etc.
(regardless of
purpose), or any other overhead structure put in place for the purpose of
supporting a
light fixture. The term "industrial" is used in order to differentiate from
residential
lighting or the like. Neither of these terms is to be taken as limiting.
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The term "power-related components" includes ballasts, capacitors, ignitors
and other devices for creating the proper electrical power usable for a
selected lamp,
such as high-intensity discharge (H]ID) lamps of various kinds.
The term "substantially enclosed," as used with respect to space within the
housing, means closed in the sense that inflow and outflow of air are impeded
even if
the space is not fully sealed. The impeding of air flow is such as would serve
to
suppress combustion if it were to occur.
The terms "top" and "base" used herein with reference to the fixture, or parts
thereof, assume the normal use orientation of the fixture. The simplicity of
the
housing retains certain advantages, including ease of manufacturing and
service,
compactness, pleasing in appearance, and ease of assembly, as disclosed in
United
States Patent No. 6,394,869 (Method For Manufacture of Overhead Light
Fixture).
The overhead industrial light fixture described herein, in its various forms,
overcomes certain problems and shortcomings of the prior art, including those
referred to above.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings illustrate preferred embodiments which include the above-noted
characteristics and features of the overhead industrial light fixture
described herein.
The invention will be readily understood from the descriptions and from the
drawings,
in which:
FIGURE 1 is a perspective view of a preferred industrial light fixture in
accordance with this invention.
FIGURE 2 is an exploded perspective view of the device of FIGURE 1.
FIGURE 3 is a cross-section of the housing of the device in FIGURE 1.
FIGURE 4 is a partial cross-section of the housing of the device in FIGURE 1.
FIGURE 5 is further partial cross-section of the housing of the device in
FIGURE 1.
FIGURE 6 is a top perspective view of the base member of the housing of the
device of FIGURE 1.
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FIGURE 7 is yet another perspective view of the base member of the housing
of the device of FIGURE 1.
FIGURE 8 is a partial view of the inside of the top member of the housing of
the device of FIGURE 1.
DETAIILED DESCRIPTION OF PREFERRED EMBODIMENTS
The drawings illustrate an overhead industrial light fixture 10 which
includes:
a housing I 1 with a top member 13 and a base member 15; power-related
components
including a ballast 17, a capacitor 19, and an ignitor 21; spring-spacer
apparatus 23; a
socket mount 25; a lamp-mounting socket 27; and a reflector 29. Such elements
are
best seen in FIGURES 1 and 2.
As seen in FIGURES 1 and 3, in one aspect of the invention base member 15
and top member 13, each formed of die-cast metal, are configured to provide
mating
engagement thereby forming a substantially enclosed space.
Referring to FIGURES 3-5, this embodiment employs housing 11 having top
and base members, 13 and 15, respectively, and together top and base members
form a
space. Top member 13 includes a top wall 31 and downwardly-extending, space-
surrounding sidewalls 33 integral with top wall 31. Base member 15 has a first
upwardly-extending middle portion 35 integral therewith which forms a housing
recess 37.
In one aspect of the invention, portions of housing 11 form a vertical airflow
thermal chimney 39, FIGURES 3-5 and 8, immediately adjacent to recess 37.
Vertical
airflow thermal chimney 39 extends through housing 11 from bottom to top
whereby
heat transfer to thermal chimney 39 and heat-dissipating airflow to the
atmosphere are
facilitated.
Referring next to FIGURES 3 and 5, in this embodiment base member 15
includes an annular lower chimney portion 45 terminating in a top edge 47. Top
member 13 includes an annular upper chimney portion 49 terminating in a lower
edge
51 adjoining top edge 47.
In another aspect of the invention, housing 11 includes first and second
opposite endwalls, 53 and 55 respectively. Middle portion 35 of base member 15
and
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thermal chimney 39 together divide the space into a first region 57 adjacent
to first
endwall 53 and a second region 59 adjacent to second endwall 55. Power-related
components include ballast 17 in first region 57 and capacitor 19 in second
region 59.
Referring further to FIGURES 3-5 and 7, there is shown an embodiment of the
invention wherein top member 13 is hinged with respect to base member 15 at
one of
the endwalls. Base member 15 and top member 13 have first and second mating
hinge members, 61 and 63 respectively, each integrally formed therewith along
adjacent edges thereof.
Before assembly, top member 13 and base member 15 are formed of die-cast
metal. Spring-spacer apparatus 23 are positioned at their assigned locations.
Next,
ballast 17 is placed at its assigned location and is secured to spring-spacer
apparatus
23. Capacitor 19 is positioned at its assigned location on a capacitor bed 67
and is
secured to base member 15 by a spring-bracket 69.
Socket mount 25 is secured with respect to base member 15. Socket mount 25
supports lamp-mounting socket 27 within housing 11.
Assembly continues by hingedly connecting top member 13 to base member
15. Base member 15 is then secured to top member 13 by first and second mating
hinge members, 61 and 63. This substantially completes assembly of light
fixture 10.
Reflector 29 can be attached to light fixture 10 while preparing for
installation
at a job site. In some cases, however, reflector 29 may be attached to light
fixture 10
immediately upon completion of attachment of base member 15 to top member 13.
When assembly is completed, light fixture 10 is ready for packaging and
shipment.
The die-cast metal used in forming top member 13 and base member 15 is
preferably Aluminum. Acceptable power-related components and other components
used in manufacture of light fixture 10 are known to those skilled in the art.
The low profile which is made possible by recessing socket 27 into housing 11
allows the vertical dimension of housing 11 to be as low as 4.5 to 6 inches,
even when
using electrical components which are standard in overhead industrial light
fixtures.
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While the principles of this invention have been described in connection with
specific embodiments, it should be understood clearly that these descriptions
are made
only by way of example and are not intended to limit the scope of the
invention.
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